Java program to find the absolute difference between diagonal and reverse diagonal of a matrix

Problem: Java program to find the absolute difference between diagonal and reverse diagonal of a matrix.

Given a square matrix of size , calculate the absolute difference between the sums of its diagonals.

Input Format

The first line contains a single integer, . The next  lines denote the matrix's rows, with each line containing space-separated integers describing the columns.

Constraints

Output Format

Print the absolute difference between the two sums of the matrix's diagonals as a single integer.

Sample Input

3
11  2   4
4   5   6
10  8 -12

Sample Output

15

Explanation

The primary diagonal is:

11
   5
     -12

Sum across the primary diagonal: 11 + 5 - 12 = 4

The secondary diagonal is:

     4
   5
10

Sum across the secondary diagonal: 4 + 5 + 10 = 19 
Difference: |4 - 19| = 15

Solution Program:

package com.rohan.test;

import java.util.Scanner;

public class Matrix {

    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        int n = in.nextInt();
        int sum1 = 0, sum2 = 0;
        int a[][] = new int[n][n];
        for(int a_i=0; a_i < n; a_i++){
            for(int a_j=0; a_j < n; a_j++){
                a[a_i][a_j] = in.nextInt();
            }
        }
        for(int i = 0; i < n; i++) {
            for (int j = 0; j < n; j++) {
                if(i == j) {
                   sum1 += a[i][j];
                }
                if(i == ((n-j)-1)) {
                sum2 += a[j][i];
            }
            }
        }
        System.out.println(Math.abs(sum1 - sum2));
    }
}


Input:

3
11  2   4
4   5   6
10  8 -12

Output:

15